Elemental mapping
An element map is an image showing the spatial distribution of elements in a sample. Because it is acquired from a polished section, it is a 2D section through the unknown sample. Element maps are extremely useful for displaying element distributions in textural context, particularly for showing compositional zonation.
How it works—Element mapping
One can use either an EDS or WDS system to produce an element map. Either way, the image is produced by progressively rastering the electron beam point by point over an area of interest. Think of an element map as a pixel by pixel (bitmap) image based on chemical elements. Resolution is determined by beam size, and relative response of each element is determined by how long the beam dwells on each point (and of course the actual concentration). Greater distinction can be made by longer analysis, but at the cost of time.
In many cases, adequate element maps can be acquired by EDS systems. This is typically a faster approach, but sacrifices resolution and detection limits. The best element maps are acquired using a WDS system on an electron microprobe, but the trade-off in using the spectrometers is longer acquisition time....
